mersenneforum.org Primes of the form (b+-1)*b^n+-1 and b^n+-(b+-1)
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 2020-02-09, 22:36 #155 carpetpool     "Sam" Nov 2016 23·5·7 Posts
2020-02-11, 03:58   #156
sweety439

Nov 2016

3·647 Posts

Quote:
 Originally Posted by carpetpool
Well, can you give all data for (b-1)*b^n-1, (b-1)*b^n+1, (b+1)*b^n-1, and (b+1)*b^n+1 for the b that you have searched? Besides, you seems have also searched the generalized repunit numbers (b^n-1)/(b-1) and (b^n+1)/(b+1), can you give all data for these two forms for the b that you have searched?

2020-02-11, 04:17   #157
carpetpool

"Sam"
Nov 2016

1000110002 Posts

Quote:
 Originally Posted by sweety439 Well, can you give all data for (b-1)*b^n-1, (b-1)*b^n+1, (b+1)*b^n-1, and (b+1)*b^n+1 for the b that you have searched? Besides, you seems have also searched the generalized repunit numbers (b^n-1)/(b-1) and (b^n+1)/(b+1), can you give all data for these two forms for the b that you have searched?
I sieved the following sequences, up to the following limits:

2*3^n+1 up to n = 5M
4*3^n+1 up to n = 2.5M

BTW, Ryan found more terms for 2*3^n+1:

https://primes.utm.edu/primes/page.php?id=130431
https://primes.utm.edu/primes/page.php?id=130429

Feel free to update your text files if you want. I will let you know when I start testing primes of the form (b+-1)*b^n+-1 and/or b^n+-(b+-1). To make matters simple, I am only focusing on those b that are a power of 3.

Edit: sweety439, I should inform you that I am no longer searching for repunit-PRPs as it was a couple years ago since I found a PRP large enough for http://primenumbers.net/. (Yes, I still search for PRPs in general, but they don't have any mathematical description so they are not submitted to the PRP top).

Last fiddled with by carpetpool on 2020-02-11 at 04:25

2020-02-11, 11:05   #158
sweety439

Nov 2016

3·647 Posts

Quote:
 Originally Posted by carpetpool I sieved the following sequences, up to the following limits: 2*3^n+1 up to n = 5M 4*3^n+1 up to n = 2.5M BTW, Ryan found more terms for 2*3^n+1: https://primes.utm.edu/primes/page.php?id=130431 https://primes.utm.edu/primes/page.php?id=130429 Feel free to update your text files if you want. I will let you know when I start testing primes of the form (b+-1)*b^n+-1 and/or b^n+-(b+-1). To make matters simple, I am only focusing on those b that are a power of 3. Edit: sweety439, I should inform you that I am no longer searching for repunit-PRPs as it was a couple years ago since I found a PRP large enough for http://primenumbers.net/. (Yes, I still search for PRPs in general, but they don't have any mathematical description so they are not submitted to the PRP top).
You are really searching the generalized repunit (probable) primes, see https://oeis.org/history?user=Paul%20Bourdelais, you found the PRPs (3^1896463+1)/4, (6^1365019-1)/5, and (37^168527-1)/36 recently, and you are seems searching generalized repunit (probable) primes for all bases -101<=b<=101

2020-02-11, 23:38   #159
carpetpool

"Sam"
Nov 2016

23×5×7 Posts

Quote:
 Originally Posted by sweety439 You are really searching the generalized repunit (probable) primes, see https://oeis.org/history?user=Paul%20Bourdelais, you found the PRPs (3^1896463+1)/4, (6^1365019-1)/5, and (37^168527-1)/36 recently, and you are seems searching generalized repunit (probable) primes for all bases -101<=b<=101
Sweety, there are multiple Paul's on this forum (and elsewhere). That's not my PRP account. (Look at the https://primes.utm.edu/ links I posted and compare it with what's on my http://primenumbers.net/).

Last fiddled with by carpetpool on 2020-02-11 at 23:40

 2020-02-12, 07:55 #160 kar_bon     Mar 2006 Germany 2,801 Posts I've updated the Wiki entry for 2*3^n+1, but I don't know the exact range checked so far, at OEIS there's no limit given. @carpetpool: You could update your found primes and ranges tested there by yourself. Also you could reserve it there, too.
 2020-05-07, 22:27 #161 matzetoni     Feb 2019 3·19 Posts huge disappoinment Okay, so Propper took on 4*3^n+1 without looking for / asking / ignoring my reservation and has now submitted two new primes to T5K. I now officially wasted a year of effort (and electricity). Even more bad, he found a mega prime, which I'd have found in literally a few days and it would have been my first mega prime. So that's the story. I'll abandon the search.
 2020-05-09, 00:32 #162 carpetpool     "Sam" Nov 2016 28010 Posts I'm working on a posting sieve files for some sequences so situations like these won't occur again. Anybody can test them as long as they reserve that sequence. I'm expecting to have some sequences out in a week or two.
 2020-05-15, 18:33 #163 carpetpool     "Sam" Nov 2016 23·5·7 Posts Sieving/Reserving MP 11 Ranges will be updated and posted later.

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